This invention relates to a deployment system for aerosurfaces such as wings or fins.
Aerospace vehicles, such as missiles and rockets, are conventionally provided with wings or fins for lift, flight stabilization, and control. Such laterally or vertically extending aerosurfaces can pose problems of space requirements and drag when they are stowed and carried by aircraft. In order to avoid these disadvantages, many current aerospace vehicle designs employ aerosurfaces which are folded along the vehicle's side or body for storage, handling, and transport, and then deployed outwards to an open, swept position upon launching for flight. For example, U.S. Pat. No. 4,664,339 which issued to Crossfield on May 12, 1987, (hereinafter '339), discloses a side-mounted missile wing which, when deployed, rotates upwardly from the horizontal stowed position into a vertical position. U.S. Pat. No. 3,063,375 which issued to Hawley et al on Nov. 13, 1962, (hereinafter '375), discloses a side-mounted fin folding arrangement which is erected by a rotary movement. For both the '339 and '375 patents, as the aerosurfaces unfold they initially experience airflow normal to the aerosurface which would cause divergence under moderate or high speed airflow and significant structural problems at the root; such an approach could allow air loads to tear the aerosurface off the missile if deployed during flight due to the high bending moments at the root.
U.S. Pat. No. 4,336,914 which issued to Thomson on Jun. 29, 1982, (hereinafter '914), discloses a side-mounted deployable wing assembly having an inner wing segment and an outer wing segment; the inner wing segment is hinged longitudinally to the body of the aircraft while the outer wing segment is hinged by a pin perpendicular to the surface of the wing segments at the junction. This arrangement requires separate mechanisms and complicated cabling to deploy the entire wing assembly--one to pivot and unfold the inner wing segment, and another to deploy the outer wing segment. Such cumbersome arrangement of multiple deployment mechanisms and cables multiple areas of stress concentration; this, in turn, increases the likelihood of inefficiency, low performance, and failure. In addition to requiring complex, costly machining, the outer and inner wing segments in the '914 invention result in a relatively low wing root stiffness due to the joint design; low wing root stiffness is a distinct disadvantage in modern aerospace vehicles which experience high aerodynamic loads and dynamic pressures. Therefore, this type of invention would be severely limited to the flight speeds for which it could be utilized.
Thus, there is a need in the art for aerosurface deployment mechanisms with a minimum number of parts which do not initially open flatwise to the airflow, which have relatively high wing root stiffness, which are deployed with a single mechanism, and which are capable of being used at high in-flight speeds.